The effects of global warming are pronounced at high northern latitudes, where the warming trend observed for the past decades is almost twice as the global average. Most glaciers in Svalbard (High Arctic ... [more ▼]

The effects of global warming are pronounced at high northern latitudes, where the warming trend observed for the past decades is almost twice as the global average. Most glaciers in Svalbard (High Arctic) have been retreating and thinning since the end of the Little Ice Age in the late 19th century, and retreat rates have increased substantially in the last decades. As a glacier retreats, it systematically exposes new terrestrial habitats for the colonization by pioneering (micro)organisms. Distance from the glacier terminus can be used as a proxy for time since deglaciation, which makes glacier forefields well suited for the study of primary succession. In the present study, we investigated the successional trajectories of cyanobacterial communities along a 100-year deglaciation gradient in the forefield of two Svalbard glaciers (Ebba- and Hørbyebreen). Cyanobacterial abundance was assessed by epifluorescence microscopy and cyanobacterial diversity was investigated by pyrosequencing of partial 16S rRNA gene sequences. Filamentous cyanobacteria were more abundant than unicellular and heterocystous cyanobacteria in both forefields, and an increase in the abundance of cyanobacteria was observed along the deglaciation gradients. Pseudanabaenales was the most OTU-rich order, followed by Chroococcales, Oscillatoriales, Synechococcales, Nostocales and Gloeobacterales. At the genus level, classified phylotypes were assigned to Leptolyngbya, Phormidium, Nostoc, Pseudanabaena, Chroococcidiopsis and Microcoleus. Interestingly, OTU richness increased along the deglaciation gradient in Ebbabreen, but an inverse correlation was observed in Hørbyebreen. Beta diversity estimations indicated contrasting cyanobacterial phylogenetic structures along the temporal gradient, with a clear separation of initial (10-20 years), intermediate (30-50) and advanced (80-100) communities. Time since deglaciation accounted for around 25% of the phylogenetic variability in both forefields, with organic carbon content also explaining a significant proportion of community turnover along the deglaciation gradients. Taxonomic composition was somewhat constant along the deglaciation gradient, but OTUs associated with initial communities were related to sequences predominantely restricted to polar biotopes, while advanced communities included phylotypes related to cosmopolitan taxa. [less ▲]

The bacterial and microeukaryotic biodiversity were studied using pyrosequencing analysis on a 454 GS FLX+ platform of partial SSU rRNA genes in terrestrial and aquatic habitats of the Sør Rondane ... [more ▼]

The bacterial and microeukaryotic biodiversity were studied using pyrosequencing analysis on a 454 GS FLX+ platform of partial SSU rRNA genes in terrestrial and aquatic habitats of the Sør Rondane Mountains, including soils, on mosses, endolithic communities, cryoconite holes and supraglacial and subglacial meltwater lenses. This inventory was complemented with Denaturing Gradient Gel Electrophoresis targeting Chlorophyta and Cyanobacteria. OTUs belonging to the Rotifera, Chlorophyta, Tardigrada, Ciliophora, Cercozoa, Fungi, Bryophyta, Bacillariophyta, Collembola and Nematodawere present with a relative abundance of at least 0.1% in the eukaryotic communities. Cyanobacteria, Proteobacteria, Bacteroidetes, Acidobacteria, FBP and Actinobacteria were the most abundant bacterial phyla. Multivariate analyses of the pyrosequencing data revealed a general lack of differentiation of both eukaryotes and prokaryotes according to habitat type. However, the bacterial community structure in the aquatic habitats was dominated by the filamentous cyanobacteria Leptolyngbya and appeared to be significantly different compared with those in dry soils, on mosses, and in endolithic habitats. A striking feature in all datasets was the detection of a relatively large amount of sequences new to science, which underscores the need for additional biodiversity assessments in Antarctic inland locations. [less ▲]

The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has ... [more ▼]

The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has been long known that the rate of dispersal to an ecosystem can significantly influence ecosystem dynamics, and that aerial transport has been identified as an important source of biological input to remote locations. With the considerable effort devoted in recent decades to understanding atmospheric circulation in the south-polar region, a unique opportunity has emerged to investigate the atmospheric ecology of Antarctica, from regional to continental scales. This concept note identifies key questions in Antarctic microbial biogeography and the need for standardized sampling and analysis protocols to address such questions. A consortium of polar aerobiologists is established to bring together researchers with a common interest in the airborne dispersion of microbes and other propagules in the Antarctic, with opportunities for comparative studies in the Arctic. [less ▲]

Antarctica is essentially a microbial continent. A surprisingly large biodiversity of adapted microorganisms lives permanently in various biotopes of the ice-free areas (about 44,000 km2). Based on ... [more ▼]

Antarctica is essentially a microbial continent. A surprisingly large biodiversity of adapted microorganisms lives permanently in various biotopes of the ice-free areas (about 44,000 km2). Based on molecular methods and microscopic observations, important findings like the presence of potentially endemic taxa, their survival in glacial refugia since the continent moved away from Australia and South America, and the determination of biogeographic patterns have been inferred. Moreover, Antarctic microorganisms may contain novel molecules with potentially pharmaceutical or biotechnological interest. However, microbial habitats are under pressure as a result of nthropogenic introductions. Indeed, as a consequence of human presence, non-indigenous microorganisms are released from bodies, clothing, cargo and food into the environment (Cowan et al. 2011). The increase of tourism and its diversification from coastal cruises to adventurous expeditions into the continent, as well as the increase of research stations and associated impacts, constantly create new ‘entry points‘ for microbial contamination (Chown et al. 2012). The impacts of such introductions are still unknown, and might lead to a loss of the native microbial biodiversity, or its modification by lateral gene transfer. The technical progresses in molecular methodologies, like we currently see with Next Generation Sequencing (NGS), mean that very sensitive high-throughput analyses will become increasingly accessible. They have the potential to describe the microbial communities with unprecedented details without preconceived expectations. However, by that time, we might have lost the pristine Antarctic areas that would enable the scientists to study the native microbial flora, its functioning and properties. The Protocol on Environmental Protection of the Antarctic Treaty foresees the designation of Antarctic Specially Protected Areas (ASPA) to protect “outstanding environmental, scientific, historic, aesthetic, or wilderness values, any combination of those values, or on- going or planned scientific research” (http://www.ats.aq/e/ep_protected.htm). However, the designation of ASPAs has not followed a systematic planning, and often focused on the conservation of large animals or higher plant communities. Microorganisms have the handicap of generally being invisible without a microscope and relevant expertise, and needing molecular methods to determine their identity. Terrestrial habitats are protected in 55 out of the 72 existing ASPAs (in total less than 700 km2), mostly based on the need to protect vascular plants and bryophyte communities (Shaw et al. 2014). In 28 ASPAs, the protection targets the lichens, whereas microalgae are protected in 16 ASPAs, cyanobacteria in 7 and snow microalgae in 3. Only 8 ASPAs mention ‘Microbial habitats’, ‘microbial communities’ or ‘soil and lake microflora’. One tool of the Protocol that could be specifically used to protect microbial habitats is the creation of inviolate areas where no visitation is permitted (inside ASPAs, for example). These zones could be set aside for future research (Hughes et al. 2013) and become extremely valuable. After a few decades, they would be unique examples of truly pristine habitats, representative of the native microbial diversity and processes. Such an option would necessitate discussions and consensus with scientists of other disciplines to select these regions, and careful management protocols of the sites and their vicinity (Hughes et al. 2015). In addition, gaps in knowledge should be addressed, like the extent of transportation of microorganisms by natural means (winds, birds...) (e.g. Pearce et al. 2009), and the probability of subsequent colonization of new areas by microorganisms coming from other Antarctic regions or from outside Antarctica. Let’s hope that the dialogue between scientists and policy makers will enable to improve the conservation of Antarctic microbial diversity and safeguard the possibility to study these unique communities in the future with the most advanced techniques of the time. The outcome of these discussions might also be of interest for Arctic and alpine regions. [less ▲]

In Polar Regions, Cyanobacteria represent key primary producers and are the main drivers of the food webs in a wide range of aquatic to terrestrial habitats. For example, they form benthic microbial mats ... [more ▼]

In Polar Regions, Cyanobacteria represent key primary producers and are the main drivers of the food webs in a wide range of aquatic to terrestrial habitats. For example, they form benthic microbial mats in lakes and soil crusts in terrestrial biotopes. They have adapted to their environment, and may present interesting features to survive freeze/thaw cycles, seasonally contrasted light intensities, high UV radiations, dessication and other environmental stresses. The BCCM/ULC public collection funded by the Belgian Science Policy Office since 2011 aims to gather a representative portion of the polar cyanobacterial diversity with different ecological origins (limnetic microbial mats, soil crusts, cryoconites, endoliths, etc.). The collection is available for researchers to study the taxonomy, evolution, adaptations to extreme environmental conditions, and genomic make-up. It presently includes 200 cyanobacterial strains, with 123 being of polar origin (catalogue: http://bccm.belspo.be/catalogues/ulc-catalogue-search). The morphological identification shows that the strains belong to the orders Synechococcales, Oscillatoriales, Pleurocapsales, Chroococcidiopsidales and Nostocales. The large diversity is also supported by the phylogenetic analyses based on the 16S rRNA sequences. This broad distribution makes the BCCM/ULC collection particularly interesting for phylogenomic studies. To this end, the sequencing of the complete genome of 16 selected strains is currently under way. In addition, cyanobacteria produce a wide range of secondary metabolites (e.g. alkaloides, cyclic and linear peptides, polyketides) with different bioactive potential (e.g. antibiotic, antiviral, anticancer, cytotoxic, genotoxic). Bioassays have shown antifungal activities of the cell extracts from strains Plectolyngbya hodgsonii ULC009 and Phormidium priestleyi ULC026. The potential of the polar strains to produce cyanotoxins and other secondary metabolites is currently being studied by ELISA, LC-MS and the detection of genes involved in their production. Due to the geographic isolation and the strong environmental stressors of the habitat, the exploration of these metabolites in Antarctic cyanobacterial strains seems promising for biotechnology or biomedical applications (Biondi et al. 2008). In summary, the BCCM/ULC public collection could serve as a Biological Resource Centre (OECD 2001) to conserve and document the biodiversity of polar cyanobacteria, as well as a repository for discovery of novel bioactive compounds. REFERENCES Biondi, N., Tredici, M., Taton, A., Wilmotte, A., Hodgson, D., Losi, D., & Marinelli, F. (2008) : Cyanobacteria from benthic mats of Antarctic lakes as a source of new bioactivities. Journal of Applied Microbiology, 105(1) : 105- 115 OECD (2001) Biological Resource Centres : Underpinning the Future of Life Sciences and Biotechnology. http://www.oecd.org/science/biotech/2487422.pdf [less ▲]

Cyanobacterial diversity in soil crusts has been extensively studied in arid lands of temperate regions, particularly semi-arid steppes and warm deserts. Nevertheless, Arctic soil crusts have received far less attention than their temperate counterparts. Here we describe the cyanobacterial communities from various types of soil crusts from Svalbard, High Arctic. Four soil crusts at different development stages (ranging from poorly-developed to well-developed soil crusts) were analysed using 454 pyrosequencing of the V3-V4 variable region of the cyanobacterial 16S rRNA gene. Analyses of 95660 cyanobacterial sequences revealed a dominance of OTUs belonging to the orders Synechococcales, Oscillatoriales, and Nostocales. The most dominant OTUs in the four studied sites were related to the filamentous cyanobacteria Leptolyngbya sp. Phylotype richness estimates increased from poorly- to mid-developed soil crusts and decreased in the well-developed lichenized soil crust. Moreover, pH, ammonium and organic carbon concentrations appeared significantly correlated with the cyanobacterial community structure. [less ▲]

Cyanobacteria appear as the dominant phototrophs in Antarctic terrestrial and freshwater ecosystems. Since 2011, the Belgian Science Policy Office has funded the BCCM/ULC public collection of (sub)polar ... [more ▼]

Cyanobacteria appear as the dominant phototrophs in Antarctic terrestrial and freshwater ecosystems. Since 2011, the Belgian Science Policy Office has funded the BCCM/ULC public collection of (sub)polar cyanobacteria. It is currently holding 102 Antarctic cyanobacterial strains and the catalogue is available on http://bccm.belspo.be/db/ulc_search_form.php. A Quality Management System was implemented and an ISO9001 certificate was obtained for the public deposition and distribution of strains. The strains are kept as living cultures, and their cryopreservation is in progress. The Antarctic cyanobacterial strains were isolated from samples of the three main biogeographic provinces. The purpose of this public collection is to gather a representative portion of the cyanobacterial diversity with different ecological origins (limnetic microbial mats, soil crusts, cryoconites, endoliths, etc.) and make it available for researchers to study the diversity, evolution, adaptations to the environmental conditions, and genomic make-up. Three cyanobacterial orders are represented: Chroococcales, Oscillatoriales and Nostocales. This is particularly important in view of the emerging use of metagenomic approaches on environmental samples, where the comparisons with the genome sequences from well-defined strains is very useful. They could also serve as references for compounds such as fatty acids and pigments. In addition, cyanobacteria produce a range of secondary metabolites (e.g. alkaloides, cyclic and linear peptides, polyketides) with different bioactive potential (e.g. antibiotic, antiviral, anticancer, cytotoxic, genotoxic). Bioassays have shown antifungal activities of the cell extracts of strains Plectolyngbya hodgsonii ULC009 and Phormidium priestleyi ULC026. Due to the geographic isolation and the strong environmental stressors of the habitat, the exploration of these metabolites in Antarctic cyanobacterial strains seems especially promising for biotechnology or biomedical applications. In summary, the BCCM/ULC public collection could serve as a general reference for Antarctic cyanobacteria with multiple applications, as well as a resource for novel bioactive compounds. [less ▲]

Open Top Chambers are passive warming systems used to experimentally assess the effect of climate change on terrestrial ecosystems, and they were used in several Antarctic regions to study the response of ... [more ▼]

Open Top Chambers are passive warming systems used to experimentally assess the effect of climate change on terrestrial ecosystems, and they were used in several Antarctic regions to study the response of biotic communities. In the BELSPO BELDIVA project, OTCs were used in continental Eastern Antarctica, where environmental conditions are very extreme. In January 2010, 8 Open-Top Chambers (OTC) were installed in four ice-free regions of the Sör Rondane Mountains, namely on the Utsteinen ridge, the Tanngarden granite outcrop, the Teltet nunatak and the fourth nunatak of the Pingvinane range. [less ▲]

Filamentous cyanobacteria are keystone species in Antarctic lake ecosystems; they are the basis of the simple foodwebs, play a crucial role in biogeochemical cycling and form the structure of benthic ... [more ▼]

Filamentous cyanobacteria are keystone species in Antarctic lake ecosystems; they are the basis of the simple foodwebs, play a crucial role in biogeochemical cycling and form the structure of benthic microbial mats which act as habitats for other prokaryotic and (micro-eukaryotic biota. Despite this, little is known about their diversity, adaptation and survival strategies in the extreme Antarctic conditions. We studied the uncultivated prokaryotic diversity using a 454 metagenomic analysis at the 16S rRNA level (V1-V3 region) in Continental Antarctic lakes situated along a conductivity gradient (0.014-142.02 mS/cm). The quality and length of the amplicons was analyzed with a custom-made Mothur pipeline and the resulting sequences were mapped against the Greengenes database, which includes CyanoDB. Almost 27% of the sequences could be assigned to the phylum of the cyanobacteria. The most abundant cyanobacteria in the dataset belonged to the genera Microcoleus, Leptolyngbya, Pseudanabaena, Nodularia and Phormidum. Some 16S rRNA types (at the 97% similarity level), such as sequences related to Leptolynbya antarctica, were present in both freshwater and hypersaline lakes. In order to further investigate this distribution, we isolated filaments of Leptolyngbya from seven lakes with conductivities ranging between 26.8 mS/cm and 0.038 mS/cm. The complete 16S rRNA and ITS genes of the isolates were subsequently sequenced. We found several 16S types related to different lineages of filamentous cyanobacteria in the seven lakes that were supported by ITS data. Two 16S types, belonging to a Leptolyngbya antarctica and Leptolyngbya sp., were each present in two different freshwater lakes. Two different 16S types, both belonging to Leptolynbya antarctica were present in a freshwater and hypersaline lake, which indicates a high ‘intraspecific’ molecular diversity. In order to better understand the adaptation and/or wide tolerance to osmotic stress, we are currently performing ecophysiological experiments with these isolates aimed at assessing the potential local adaptation of these strains to conductivity and desiccation. [less ▲]

In continental Antarctica, the environnmental conditions are extreme and only microbial organisms can withstand them. Currently, the majority of OTCs experiments are being held in Maritime Antarctica but ... [more ▼]

In continental Antarctica, the environnmental conditions are extreme and only microbial organisms can withstand them. Currently, the majority of OTCs experiments are being held in Maritime Antarctica but it would be interesting to have such data for the continental part of Eastern Antarctica. To monitor the response of the microbial communities to local simulations of climate change, 8 Open-Top Chambers (OTC) were installed close to the Princess Elisabeth station, in the Sor Rondane Mountains in January 2010. They are located on the Utsteinen ridge, the Tanngarden granite outcrop, the Teltet nunatak and the fourth nunatak of the Pingvinane range. In each location, two OTCs and a control area were established. Temperature and humidity loggers were installed inside the OTCs and outside, in the control areas, to estimate the environmental changes induced by the OTCs. [less ▲]

A special cluster of filamentous, false-branched cyanobacteria, isolated from littoral mat samples in coastal lakes of the Larsemann Hills region (coll. by D. Hodgson) was studied by a polyphasic approach ... [more ▼]

A special cluster of filamentous, false-branched cyanobacteria, isolated from littoral mat samples in coastal lakes of the Larsemann Hills region (coll. by D. Hodgson) was studied by a polyphasic approach. This morphotype has several characters corresponding to the traditional genera Leptolyngbya (morphology of trichomes), Pseudophormidium (type of false branching) or Schizothrix (occasional multiple arrangement of trichomes in the sheaths). However, this cluster of strains is distinctly isolated according to its phylogenetic position (based on 16S rRNA gene sequences), and thus, a separate generic classification is justified. The cytomorphology of this generic entity is also characteristic. Therefore, a new genus (Plectolyngbya with the type species P. hodgsonii) was described. [less ▲]